AB1568 ENTHESITIC INVOLVEMENT IN PATIENTS WITH SAPHO SYNDROME. ULTRASOUND EVALUATION USING THE MASEI INDEX
Authors: Á. Andreu-Suárez, B. A. Blanco Cáceres
Journal: Annals of the Rheumatic Diseases (2023)

<h3>Background</h3> SAPHO syndrome (synovitis, acne, pustulosis, hyperostosis, and osteitis) is a rare disease with a prevalence of less than 1 in 10,000 [1]. Among its musculoskeletal manifestations, enthesis involvement has been observed, which, along with the axial manifestations, has led many authors to consider it as part of the spondyloarthropathies group of diseases. Ultrasound assessment of enthesis is known to be more sensitive and specific than physical examination. The Madrid Sonographic Enthesitis Index (MASEI) is one of the most widely used tools for enthesis evaluation in spondyloarthropathies [2]. It examines six entheses (quadriceps, proximal and distal patellar, Achilles, plantar fascia, and triceps) and assesses six possible elementary lesions defined by OMERACT [3], plus Doppler. This allows the assessment of both inflammatory activity and structural damage (structure, thickness, erosions, calcifications, and bursitis) [4]. While there have been some ultrasound studies on enthesic involvement in SAPHO, demonstrating damage even in asymptomatic patients [5], there is currently no validated ultrasound index for enthesis evaluation in this disease. <h3>Objectives</h3> The aim of this study is to describe the ultrasound findings of SAPHO Syndrome patients' entheses using the MASEI index. <h3>Methods</h3> This is a descriptive, cross-sectional, single-center study, carried out in the Rheumatology Service of the Ramón y Cajal Hospital (Madrid, Spain). A convenience sampling was carried out, including all patients with SAPHO under active follow-up in our clinics. <h3>Results</h3> 12 patients were included (83.3% women), with a mean age of 52.41 (±9.4) years at the time of the study. 66.7% were smokers, and 25% ex-smokers. The mean BMI was 26.62 (±5.69). The average number of painful entheses was 0.92 (±1.24) and no swollen entheses were found. 25% of the patients had been diagnosed with previous clinical enthesitis. 38.5% of the patients had a positive MASEI score (&gt;18). The mean score of the MASEI index was 20.42 (±11.02). Of this score, only a mean of 2 (±1.5) was found in the Doppler study; while a mean of 18.25 (±14.50) corresponded to structural damage. The involvement within the different explored entheses is described in Table 1. The greatest involvement was found in the distal patellar enthesis (6.58 ± 3.75) (Figure 1). <h3>Conclusion</h3> The patients with SAPHO Syndrome in follow-up at Ramón y Cajal hospital were found to have ultrasound entheseal abnormalities using the MASEI index. The results revealed a clear predominance of structural damage over the presence of active lesions. Further studies with larger sample size are necessary to fully comprehend the involvement of entheses in SAPHO syndrome. <h3>References</h3> [1]Nguyen MT, Borchers A, Selmi C, Naguwa SM, Cheema G, Gershwin ME. The SAPHO Syndrome. Semin Arthritis Rheum. 1 de diciembre de 2012;42(3):254-65. [2]M. Cristina Mata Arnaiz, Eugenio de Miguel Mendieta. Utilidad de la ecografía en la evaluación de las entesis periféricas en las espondiloartritis. Reumatología Clínica. Volume 10, Issue 2, 2014, Pages 113-119. [3]De Miguel E, Cobo T, Muñoz-Fernández S, Naredo E, Uson J, Acebes JC, et al. Validity of enthesis ultrasound assessment in spondylarthropathy. Ann Rheum Dis. 2009;68:169–74. [4]Macía-Villa C, Falcao S, Medina J, De Miguel E. Ultrasonography of enthesis in psoriatic arthritis: a descriptive and reliability analysis of elemental lesions and power Doppler subtypes. Scand J Rheumatol. 2019 Nov;48(6):454-459. [5]Queiro, R, Alonso, S, Alperi, M et al. Entheseal ultrasound abnormalities in patients with SAPHO syndrome. Clin Rheumatol 31, 913–919 (2012). <h3>Acknowledgements:</h3> NIL. <h3>Disclosure of Interests</h3> África Andreu-Suárez Grant/research support from: Amgen, Boris Anthony Blanco Cáceres Speakers bureau: MSD, Novartis, Janssen, Grant/research support from: Novartis, MSD, Lilly, Pfizer, Janssen.